Dynamo-electric machine



(No Model.)

R. H. MATHER.

DYNAMO ELECTRIC MAGHINE. No. 326.575. Patented Sept. 22, 1885.

Wmewes lvwmtor.

U ITED STATES PATENT OFFICE.

RICHARD H. MATHER, OF \VINDSOR, CONNECTICUT.

DYNAMO-ELECTRIC MACHINE.-

SPECIFICATIQN forming part 'of Letters Patent No. 326,575, dated September 22, 1885.

Application filed November 20, 1984. (N0 model.)

T0 all 1072,0777, it may concern: I

Be it known that I, RICHARD H. hIATHER, a citizen of the United States, residing in the town of \Vindsor, county of Hartford, and State of Connecticut, have invented certain new and useful Improvements in Dynamo Electric Machines, of which the following isa description such as will enable those who are skilled in the art to which it appertains to make and use the described invention, reference being had to the accompanying drawing, which forms a part of this specification.

This invention relates to dynamo-electric generators of that class in which the fieldmagnet is excited by an electric current in a derived circuit about the work, or, in other words, to shunt-dynamos acting as generators.

The object of this invention is to render dynamoclectric generators of the specified class self-regulating in such a sense that any such machine, on being driven with a constant speed, shall produce a uniform and constant current in the working-circuit regardless of variations of resistance in that circuit. My invention is designed to render any dynamo which embodies the same capable of operating with a constant current any number of. elec trio-arc lamps or other resistances arranged in series up to the full capacity of the machine. These results I accomplish by a compound winding of the field-magnet, whereby the latter becomes a differential electro-magnet.

I proceed to point out the best mode in which I have contemplated applying my in vention.

The accompanying drawing is a diagrammatic representation of a shunt-wound dynamoelectric generator embodying my invention, and having electric-arclamps in the main circuit.

In this drawing, F is the field-magnet, the particular form of which is unimportant in this connection. The north and south poles of the field-magnet are lettered, respectively, N and S. The arrows indicate the direction of the current. A is the armature, which is provided with commutator and brushes in the usual manner, as shown. The principal winding of the lieldanagnet, and that which determines the indicated polarity of the same, is

by means of a tine wire in a sluint-circuit about the work;- and this fact has been per mitted to determine the above classification of the present generator as shunt-wound. An additional helix, composed of wire which lies in the main circuit with the lamps or other work, is also wound upon the field-magnet, and is connected in such a manner that this helix and the shunt-helix referred to shall operate differentially as respects each other. This wire should preferably be of the same size as that which constitutes the rest of the main circuit.

It is necessary to point out more particularly the quantity of wire embraced in the coarse and fine wire coils of the field-magnet, respectively. In the construction of any particular dynamo embodying the prescntinvention, I determine these particulars in the following manner: Having constructed and arranged as a complete shunt-dynamo the several parts of the machine in hand, other than the coarsewire coil of the field-magnet, I introduce asmall artificial resistance into the shunt-circuit, for a purpose which will here inafter appear. The work which is to bepen formedby the machine may be assumed to be the operating of electric-arc lamps. I then introduce into the main circuit the maximum number of lamps which the machine can operate in a proper manner when run at the desired speed. This determines the capacity to which the completed machine will be adjusted. I next out out of circuit all the lights but one, and then ascertain by trial what quantity of coarse wire of the size selected for the purpose is sufficient when wound upon the field-magnet and placed in circuit to reduce the single remaining light to normal brightness. The wire so determined having been wound upon the field-magnet and placed in circuit in the manner shown in the drawing and already described, I turn on all the lights which the machine is intended to operate, and restore the same to normal brightness by winding upon the field-magnet, as a part of the shunt-coil shown in the drawing, so much ad ditional fine wire as may be necessary in order to produce that result. At this point I remove from the shunt-circuit so much of the artificial resistance before mentioned and introduced as is equal to the resistanceintroduced into that circuit by such addition to the fine-wire coil of the fieldmagnet. Then, again, I turn out all the lights in circuit but one, and if the single remaining light is too bright I increase the main-circuit coil, as before, until the normal brilliancy is regained. These steps determine with a fair degree of accuracy the quantity of wire which is neces sary to be embraced in the respective coils of the field-magnet in order that the proposed regulation maybe secured. If a greater degree of accuracy is desired, the above process ofsuccessive additions to said coils may be continued until accurate self-regulation 'is obtained both for a single lamp and for the maximum number of lamps which the machine is designed to operate. The remaining features of construction involved inthe present invention, as well as the appropriate electrical connections, will sufficiently appear from the drawing and from the mode of operation, as hereinafter explained.

This construction results in the following mode of operation: The field magnet operates as a differential electro-magnet, whose entire,

electromagnetic excitation varies with the re sistance in the main circuitin a manner which is the differential effect of the joint operation ofthe field-magnet coils. The intensity of the magnetic field in which the arn'lature revolves varies in the same manner. XVhen the magnetic field is strongest, the maximum number oflamps receives sufficient current to bring those lamps to standard brightness, and no more. \v'hen the field is weakest, a single lamp when placed in circuit receives sufficient current to bring the same to standard bright ness, and no more, and when the magnetic field is of any intermediate intensity the current is sufficient to bring to standard brightness that intermet'liate numberoflamps whose operation has, through the agency of said coils, affected said field in such intermediate degree.

it is well understood that in the case of a shunt dynamo which has no regulator the current in. the working-circuit diminishes as the number of lamps increases, for the reason that successive equal increments in the resistance in the working-circuit and the corresponding equal increments of current in the shunt-circuit fail to produce successive equal increments of magnetization in the field-magnet. This is especially noticeable when the latter approaches saturation. \Vhen the fieldmagnet is near thepoint of saturation, the degree of its magnetization, and hence the intensity of its field, increases less and less for each successive lamp turned on, and diminishes more and more for each successive lamp turned off, so that the light is too bright when a singlelamp is in operation, oris too dim when all the lamps are in operation; or, as is frequently the case, both of these disadvantages coexist in one and the same system. The present invention obviates this difficulty by i11- creasing the range of variation in the intensity of magnetization of the field-magnet, and by producing for every lamp turned 011 or off an approximately uniform and equal variation in that intensity, and consetpiently in the intensity of the magnetic field in which the armature revolves. In the operation of the differential field-magnet F, the tine-wire helix tends to produce in that magnet a degree of magnetization strictly proportionate to the number of lamps in operation, but without the coarse-wire helix would fall short of producing that effect, exactly as in the typical shunt-dynamo, as just explained. On the other hand, the coarse-wire helix tends to produce in the field-magnet a degree of reverse magnetization which is uniform and constant whatever be the number of lamps in circuit; hence the combined effect of the operation of the field-magnet coils with any number of lamps in circuit within the capacity of the machine is equal to the algebraic sum of the separate effects which would be produced under the same conditions by each of said differential coils without the other. The algebraic sum of these effects when a single lamp is in operation is by construction such as to produce exactly the necessary current for one lamp, and when the maximum num- .ber of lamps is in operation the algebraic sum of said effects is such as to produce exactly that current which is necessary for the maximum number of lamps. \Vhcn any intermediate number of lamps is in operation, the total magnetization produced in the field magnetthe same being, as before, the algebraic sum of the unlike electromagnetic effects of said differential coilsmay be slightly in excess of that degree of magnetization which is necessary in order to supply that intermediate number of lamps with their normal current. The discrepancy, however, is insignift cant and of no practical importance. In the operation of the present invention, the variable electro-magnetic effect of the shunt-coil is uniforn'ily reduced by the constant electromagnetic effect of the coarse-wire coil; hence the ratio in which the combined electro-magnetic effect of both coils when all. the lamps are on exceeds the combined electromagnetic effect of the same when but a single lamp is on is greater than the ratio in which the effect of the shunt-coil alone when the maximum number of lamps is on exceeds the electromagnetic effect of the same when but a single lamp is on; hence, as already indicated, the difference between the greatest and least excitation of the field-magnet constructed as above is greater than the difference between the corresponding states of alikcfield-magnet produced by the shuntcoil alone. Indeed, it is obvious that by the mode of construction above described the first-mcntioued difference can readily be made so great that the maximum magnetization of the field-magnet shall exceed the minimum magnetization of the same exactly by any desired multiple of the latter. Accordingly, in myimproved dynamo the range of variation in the intensity of the field-magnet is such as to allow for every lamp turned on or off a degree of variation which and with reference to a number of lamps which is less than the maximum number of lamps for instance, four orfiveless than the maximum number of lamps, instead of the maximum number of lamps, regarded as a maximum resistance. This modified construction results in the described regulation between the limits so taken, and the regulation without those limits needs no special attention.

I claim as my invention 1. In a dynamo-electric generator, the fieldmagnet F, consisting of a magnetic core wound as a differential electroanagnet with two coils or helices which have a constant length or resistance and constantly-closed circuit-connections, one of said coils being placed in the main or working circuit of such generat0r,and the other of said coils being placed in a derived circuit about the work, substantially in the manner and for the purpose specified.

2. In combination with a number of electricarc lamps, or other translating devices, arranged in series in theworking-circuit of a dynamo-electric generator, a field-magnet of such generator having two coils or helices which are wound in opposite directions and to a constant resistance, and are placed in constantly-closed circuits, one of said coils in series and the other in parallel with the work,

Substantially in the manner and for the purpose specified.

3. A number of electric-arc lamps, or other translating devices, in combination with a dynamo-electric machine whose field-magnet is energized by a continuous current induced by such machine and circulating about said magnet in contrary directions through two coils or helices which are of constant length or resistance, and are energized one in series and the other in parallel with said lamps or other translating devices, substantially in the manner and for the purpose specified.

4. In a dynamoelectric generator, a fieldmagnet consisting of a magnetic core wound as a differential electro-magnet with two coils or helices having constantly-closed circuitconnections, one of said coils being placed in the main or working circuit of such generator, and the other of said coils being wound to a constant resistance and placed in a shunt-circuit about the work, substantially in the man ner and for the purpose specified.

5. In a dynamo-electric generator, a fieldmagnet consisting of a magnetic core wound as a differential electro-magnet with two coils or helices, one of said coils being placed in the main circuit of such generator, and the other of said coils being wound to a constant resist ance and placed in a constantly-closed circuit about the work, substantially in the manner and for the purpose specified.

6. In a dynamo-electric generator, a fieldmagnet consisting of a magnetic core wound as a difl'erential electro-magnet with two coils or helices of constant length, one of said coils being placed in the main circuit of such generator, and the other of said coils being placed in a constantly-closed circuit about the work, substantially in the manner and for the purpose specified.

In testimony thereof I have hereunto set my hand in the presence of two subscribing witnesses.

RICHARD H. MATHER.

\Vitnesses:

WILLARD EDDY, MORGAN W. BEACH. 

